Axial face seals (or “face seals”) are used to seal two relatively rotating bodies against each other. Face seals keep dirt and other contamination from reaching sensitive parts of a machine, such as bearings, and to retain fluid within a fluid-filled housing.
Face seals are designed to be mounted and assembled as pairs in a face-to-face relationship with the two sealing rings (typically highly polished metal rings) facing each other and rotating relative to each other. Two-piece seals are considered to be particularly susceptible to misassembly, misalignment, wear and damage because the two sealing rings, both being made of metal, are prone to wear and overheating.
Face seals may be used with rubber-tracked vehicles having high travel speed, which produces high face seal temperature due to circumferential face speed. For example, the larger the seal, the larger the circumference and hence face speed, and therefore higher temperature for a given vehicle speed. Wear and overheating may be heightened in applications involving vehicles having high travel speeds.
Rubber-tracked vehicles may also experience high tractive effort and track tension. High tractive effort and high pre-load track tension place a large load on the bearings of the idler wheels. As such, large, high-capacity bearings are required. In turn, larger circumference face seals are also required for such applications.
Further, due to design constraints conventional face seal designs utilize a seal which is substantially larger than the bearing. This phenomenon is illustrated in FIG. 7 of U.S. Pat. No. 7,370,865, for example, which shows a conventional wheel assembly having a face seal 102 that is substantially larger than the bearing 190.
Accordingly, design constraints dictate a larger bearing with a smaller face seal, thereby reducing heat produced by the face seal during operation while still limiting any tension and reaction forces applied to the bearings.